Diaphragm for sound-recording and sound-reproducing instruments



Feb. 3. 1.925.

W. E. CLIFTON DIAPHRAGM FOR SOUND RECORDING AND SOUND REPRODUCINGINSTRUMENTS Filed Nov. 12, 1921 certain Patented Feb; 1,925.

`.,UNITED STATES 1,524,689 PATENT OFFICE.

'WILLIAM ERNEST CLIFTON, 0F `NOTTIN'GrHAIM, ENGLAND, ASSIGNOR T0CLIFTOPHONE LIMITED, 0F LONDON, ENGLAND.

p DIALPBAGM FOB SOUND-RECORDING AND SOUND-REPRODUCING INSTRUMENTS.

' Application led November 12, 1921. Serial No. 514,592.

]ect of the invention is to provide an imv proved means of connectionbetween the inner end of the stylus-bar and the diahragm. 4

Hitherto the inner end of the Stylus-bar, the outer end of which islitted with the needle, has generally been attened and secured to thediaphragm by means of a small nut and bolt passing .through the attenedend of the stylus-bar and the material of the diaphra in a directionsubstantiall normal to t e plane of the diaphragm. t has been found inpractice that after the diaphragm has been in use for some time ajarring noise often becomes apparent l ,which is now believed to be dueto a loosen- `ing of the connection between the stylus-bar and the-diaphra According to t e resent invention there is rovided, on one aceof the diaphra a ug or lugs which project from the iaphragm atright-angles to the surface thereof and to which the stylus-bar is,

or is to be, connected. Conveniently a strip or strips of material aresecured to one face of the diaphragm with a portion of the strip or ofeach strip projecting through an orifice in the diaphragm so as toextend at rightangles to the surface of lthe latter on the oppositesi\de of it from that to which'the strip or strips are secured, theprojecting portion or portions affording the lug or lugs aforesaid.

According to another feature of the invention a metallic'or other hardmember is-provided in contact with, or integral with, the inner end ofthe stylus-bar and extending towards the diaphragm up to or beyond theplane of the outerI face of the latter, that is to say that face of thelatter which is adjacent to the stylus-bar.

By the term hard as applied to the above-named member is meant acharacteristic of the material of the member which is hard in comparisonwith a substance like the libre of the lugs to be described hereinafter.Hard does not lnecessaril mean metallic hardness asfit may be har in thesense that box-wood or lignum vitae, for example, are hard.

Conveniently the hard member extends completely through the diaphragmwith its end exposed to the atmosphere beyond the inner face of thediaphragm, that is to say the atmosphere within the sound-box.

rlhe invention will be more clearly understood from the followidescription given by way of example o y, of .a preferred manner ofcarrying the invention into effect and read in conjunction with theaccompanying drawings, in which- Figure 1 shows a front elevation of apart of the diaphragm and the stylus-bar;

Figure 2 is a section on an enlarged scale through a part of thediaphragm only on the line 2 2 of Figure 1;

Figures 3 and 4 are views similar respectively to Figures 1 and 2 of amodified form of diaphragm;

Figure 5 is a view similar to Figure 1 of a further modiication; and

Figuresl 6-9 illustrate, on an exaggerated scale, sections through adiaphragm and stylus-'bar connection -of further modified constructionsaccording to the present invention Like reference numerals vindicatelike parts in the several figures of the drawings.

In Figures 1 and 2 a simple diaphragm is illustrated as comprising adisc 1 of 'any preferredyielding material, such as is suit.'- able fordiaphragms of this nature. The diaphragm 1 is as usual, secured within asound-box casing indicated at 2. To the back or inner surface of thedisc 1 are Secured two strips 3 of material such as libre or Celluloid,the adjacent extremities of which project at right-angles at4 through anorifice in the material of the diaphragm so as to extend beyond itsfront or outer surface.' The parts 4 constitute two lugs between whichthe inner end of the stylusbar 5' is received and to which it is securedby means of a transverse pin 6 having at one end a head 7, and at theother a nut 8 cooperating with the screw-threaded-ex-tremty of the pin6. By means of the nut 8 the lu s in the stylus-bar end can be clampedtig tly together.

In Figures 3 and 4 the connection between the inner end of thestylus-bar and the diaphragm is eli'ected through the medium of thestrips 3 having lugs 4 which project through an orifice in thediaphragm. In this illustrated application of the invention, however,the diaphragm 1 is stiEened by additional strips 9 and 10 applied -tothe same sides of it with their inner extremities abutting at the centreline of the disc 1. Over the strips 9 and 10 is secured a cover 11 ofCelluloid which completely encloses the strip. The strip 3 is secured inthis case over the cover 11 as shown clearly in Figure 4.

It will be seen that the diaphragm illustrated in Figures 3 and 4 is ofthe construction such as is described in my co-pending application Ser.blo/514,591, tiled Nov. 12, 1921, the invention is equally applicable todiaphragms constructed according to my prior applicationSer. No. 479;?79'or in fact to any type of diaphragm employed in .apparatus of theclass to which the present invention relates. y

In place of the two separate strips 3 as illustrated a single strip ofmaterial having a looped portion folded back on itselfto take .the placeof lugs 4 could be employed, withthe inner ends of the stylus-barsecured either between the trwo laps of the loop or in contact with theouter surface of one of the laps of the loop.

Instead of forming the inner end'of the stylus-bar with a flattenedportion as illustrated in Figures 1-4 to be received between or inContact withl lugs such as 4, the inner extremity of the stylus-bar can,as shown i-n Figure 5, be bifurcated so as to receive between the twoarms thus provided, the lugs such as 4` the two arms of the stylus endsand the lugs being secured together by a transverse pin similar to thatillustrated.

It is found that with the present construction the tendency to looseningat the connection of the stylus-bar with the diaphragm is largely, ifnot completely eliminated, andthe jarring noise referred to asappertaining to constructions at present generally in use is alsolargely, if not completely, eliminated.

In the construction illustrated it is found that the strips 3 or theirequivalent, owing tothe central division constituted by the formation ofthe lugs, will impart to the stiffening strips 9 and 10 a tendency tobend or flex along adiametral line crossing centrally through the'stiffening strips'parallel with the stylus-bar.

It is obvious that while the invention may be applied to any preferredform of diaphragm it is not necessary that the lugs 4 should beconstituted solely in the manner illustrated. For example, a lug or lugssimadditional to the transverse screw securmg' the parts together, or inSome instances, if t'he paste is sulicientlv adhesive. it may beemployed as the sole means of connecting the stylus-bar with the lug orlugs such as 4.

In Figure 6 the diaphragm 1 has preferably secured to it,'as before,strips such as 9 and 10, a cover 11 and other strips 3 formed with lugs4 :projecting from the diaphragm from back to front. The inner end ofthe stylus-bar, that is the end connected to the lugs 4, is of suchlength as to pass between them so that its inner extremity terminatesapproximately flush with the back of the strips 3 and is exposed to theatmosphere within. the sound-box easing. The stylus-bar'and lugs'aresecured by means of bolts and nuts 7 and 8 or their equivalent, as inthepreviously described constructions.

In Figure 7 a similar construction is shown with the exception that theextremity of the stylus-bar is not tapered.

In Figure 8 the inner end of the stylusably extends tol a positionthrough and between the lugs 4 to be exposed within the sound-boxcasing.

It is not necessary that the stylus-bar or the members such as 12 beextended completely through the diaphragm as the invention contemplatesa hardmember extending either upto or beyond the plane of the outer faceof the diaphragm and formed either as an integral extension of thestylus-bar,

v as illustrated in Figures 6 and 7 or as a separate member. Forexample, in the construction illustrated in Figure S the member 12 maybe dispensed with when the stylusbar will terminate approximately on aplane containing the front or outer face of the diaphragm. Thedimensions of the parts will be such that the lugs 4 are held tightly tother.

many of the constructions the hard member ma be tapered in the manner inwhich the sty us-bar itself is tapered in Figure 6. Preferably thetapering is from a thiclmess of approximately ten to twelve-thousandthsof an inch down to from three to fourthousandths of an inch.

When the hard member is non-tapered it is found that a Strip of metalsuch as tinned iron of from three to four-thousandths of an inch thickandapproximately one-eighth of an inch in width will give a successfulresult with, for example, a diaphragm of two inches diameter andlsayteli-thousandths of an inch thick.

In place of providing an additional hard member this may be constitutedby a metallic coating applied, for example, mechanically or byelectro-deposition as a thin layer to the inner surface of one or eachof the lugs 4.

What I claim as m invention and desire to secure by Letters atent is 1.In a diaphragm of flexible and substantially non-resilient material forsound-re- -cording and sound-reproducing instruments,

at least one stiiening element superimposed on said diaphra in theregion of its central portion an secured thereto, two-lu extending fromthe outer face of the diaphragm and at right angles thereto and eachconstituting part of a strip which extends transversely over theaforesaid stiffening element, and means to secure the inner end of astylus-bar between said lugs, substantially as described.

2. In a sound-box of the type specified, the combination of a diaphragm,articulating means projecting from the outer face of the diaphragm atright angles thereto, a stylusbar havlng its inner end connected byAsaid articulating means tothe diaphragm, and a.

hard member additional to the articulating means extending at one endtowards the diaphragm at least up to the plane of the outer face thereofand at the other end forming a close-contact co ection with the innerend of the stylus-bar, substantially as described. l

3. In a sound-box of the type specified, the combination of a diaphragm,articluating means projecting from the outer face of the diaphragm atright angles thereto, a stylus-bar having its inner end connected bysaid articulating means to the diaphragm, and a hard member additionalto the articulating means and extending at one end completely throughthe diaphragm, whereby said end is exposed to the atmosphere beyond theinner face of 'said diaphragm, and at the other end forming aclose-contact connection with the inner end of the stylus-bar,substantially as described.

4. In a sound-boxof the type specied,

the combination of a diaphragm, articulating means projecting `from theouter face of the diaphragm at right angles thereto, a stylus-bar havingits inner end connected by said articulating means to the diaphr and ahard member additional to the articulating means and extending at oneend at least up to the plane of the outer face of the diaphragm, saidend being exposed to the atmosphere beyond the inner face of saiddiaphragm, and at the other end forming a close-contact connection withthe inner end of the stylus-bar, said hard member being in the form of aflat strip whose dimension 1n a plane parallel with the length of thestylus-bar and normal to the plane of the diaphragm is large incomparison with the thickness thereof, substantially as described.

l 5. In a sound-box of the type specified, the combination of adiaphragm, articulating means projecting from the outer face of thediaphragm at right angles thereto, a stylusbar having its inner endconnected by said articulat' g means to the diaphragm, and a hard memberadditional to the articulating means and extending at one end at leastgs u to the planeof the outer face of the diap ragm, said end beingexposed to the atmosphere beyond the inner face of said diaphragm, andat the other end forming a close-contact connection with the inner endof the stylus-bar, said hard member being wedge-shaped and taperingtowards that extremity of it which approaches the diaphragxlxli,substantially as described.

6. asound-box of the type specified, the combination of a diaphragm, twolugs extending efrom the outer face of the diaphragm at right anglesthereto, a stylus-bar, the innerv end of which is secured between saidlugs, and a hard member disposed between said lugs and extending at oneend at least up to the plane of the outer face of the diaphragm, and atthe other end forming a close-contact connection with the inner end ofthe stylus-bar, substantially as described.

7. In a sound-box of the type specified, a diaphragm having an aperturein the region of its centre, a stylus-bar vhaving its inner endextending completely through said aperture, an articulating member oneend of which is parallel with and secured to the inner face of thediaphragm and the other end of which extends through the aforesaiddiaphra aperture at right angles to and beyond iii outer face of thediaphragm, and means for securing the free end of the articulatingmember to the stylus-bar, substantially as described; f I mx tureIntestimon wereo a m si a i ERNEST oN,

